The orbitofrontal cortex of the rodent is often regarded as a higher order olfactory association cortex. The hippocampal formation plays a role in the processing of spatial, as well as non-spatial information, which includes olfaction. Evidence from anatomical and behavioral studies supports the idea that these two areas are intimately linked, functionally, as well as anatomically. This suggests that the type of processing carried out by the hippocampus may mediate the type of information processing that takes place within the orbitofrontal cortex. Scant attention has been paid to the influence the hippocampal formation has on structures outside the medial temporal lobe memory system. It is becoming more obvious, however, that nearly all neocortical structures in all parts of the brain play some role in the creation, and storage, of memory representations. The main objective of the proposed series of experiments is to investigate using multiple and single unit recording studies, in conjunction with selective lesions of the hippocampal system, the interaction between medial temporal lobe structures and the orbitofrontal cortex in the processing of olfactory and spatial information. Response characteristics of neurons in the orbitofrontal cortex of normal and lesioned animals will be compared while animals perform a series of odor-guided learning and memory tasks.